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Regional tectonic stress near the San Andreas fault in central and southern California
Author(s) -
Townend J.,
Zoback M. D.
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl018918
Subject(s) - geology , clockwise , seismology , san andreas fault , lithosphere , stress field , fault (geology) , buoyancy , tectonics , stress (linguistics) , bay , pacific plate , geodesy , geometry , subduction , oceanography , rotation (mathematics) , linguistics , philosophy , physics , mathematics , quantum mechanics , finite element method , thermodynamics
Throughout central and southern California, a uniform NNE‐SSW direction of maximum horizontal compressive stress is observed that is remarkably consistent with the superposition of stresses arising from lateral variations in lithospheric buoyancy in the western United States, and far‐field Pacific‐North America plate interaction. In central California, the axis of maximum horizontal compressive stress lies at a high angle to the San Andreas fault (SAF). Despite relatively few observations near (±10 km) the fault, observations in the greater San Francisco Bay area indicate an angle of as much as 85°, implying extremely low fault strength. In southern California, observations of stress orientations near the SAF are rotated slightly counter‐clockwise with respect to the regional field. Nevertheless, we observe an approximately constant angle between the SAF and the maximum horizontal stress direction of 68 ± 7° along ∼400 km of the fault, indicating that the SAF has moderately low frictional strength in southern California.